What are the best rules, formulas and tricks in math?
I had the same math teacher for the last 4 years of high school, and he was always teaching us number tricks and random rules. Some of the favorites: I’ve always loved SohCahToa, and the finger trick for nines. Another useful one was the ASTC ( All – Sine – Cosine – Tangent) rule fron Trigonometry, to indicate which trig function is positive in that quadrant S | A —— T | C Our math teachers generally taught it as an anagram of “All Stations To Central”, but we came up with many, many variations of it over time, to the point where it is permanently fused in our brains. Another cool rule he taught us was somebody’s conundrum, which involved working out how you could work your way over a pattern of lines without going over the same line twice. If a shape has more than three t-intersections, regardless of the size, it will be impossible. These things just keep coming to mind. I’ll post some of the better ones later.
